1. Field of the Invention
This invention relates to the manufacturing method of a display panel.
2. Description of the Related Art
Generally, liquid crystal displays are used as image display devices. They are excellent in picture visibility and have high resolution and a large angle of visibility. Therefore, the demand for them is greatly increasing for use on video cameras, AV or DVD players, and car navigation systems. Such a liquid crystal display comprises a liquid crystal display panel, a drive circuit, and the like. The liquid crystal display panel comprises an array substrate, a counter substrate, a plurality of display elements, a sealing member, and a liquid crystal layer. The array substrate and counter substrate are arranged opposite to each other with a predetermined gap therebetween. The display elements are provided between the array substrate and the counter substrate. The sealing member surrounds the display elements and bonds the array substrate and the counter substrate to each other. The liquid crystal layer is held between the array substrate and the counter substrate.
The array substrate is a glass substrate. Signal lines and scanning lines are arranged on that surface of the glass substrate which faces the counter substrate. In the region surrounded by the sealing member, the signal lines intersect with the scanning lines at right angles. The signal lines and scanning lines therefore demarcate the display elements. Each signal line has one end part extending beyond the sealing member, reaching a signal-line-driving circuit connection region that lies outside the sealing member. Each scanning line has one end part extending beyond the sealing member, reaching a scanning-line-driving circuit connection region that lies outside the sealing member.
The counter substrate has another glass substrate. On the other glass substrate, a counter electrode and the like are provided. Each display element comprises a thin film transistor (TFT), a pixel electrode, a part of the liquid crystal layer, and a part of the counter electrode. The TFT is provided near the intersection of one signal lien and one scanning line. The pixel electrode is connected to the TFT. The part of the liquid crystal layer is opposed to the pixel electrode. The part of the counter electrode is opposed to the pixel electrode. The drive circuit mentioned above has a signal-line driving circuit and a scanning-line driving circuit. The signal-line driving circuit is mounted in the signal-line-driving-circuit connection region of the glass substrate, and is connected to the signal lines. The scanning-line driving circuit is mounted in the scanning-line-driving circuit connection region of the glass substrate, and is connected to the scanning lines.
In the liquid crystal display panel, the gap between the counter substrate and that surface of the sealing member which faces the array substrate may be filled with filler. The filler may be ultraviolet-curable resin applied into the gap. The liquid crystal panel is often driven at high voltages in a high-temperature and high-humidity atmosphere, particularly if used in vehicles. This is why the ultraviolet-curable resin is applied in that part of the gap which lie outside the sealing member and into which the other end parts of the signal lines and scanning lines extend. Thus, if the other end parts of the signal lines or the scanning lines, or both, extend from the sealing member, electric corrosion of the other end parts of these lines is suppressed. Such electric corrosion may result from the dew on those parts of the signal lines or scanning lines that are located outside the sealing member, or from impurity ions adhered to the signal lines or scanning lines.
As shown in, for example, Jpn. Pat. Appln. No. 6-67192, a dispenser may be used to fill the gap at the sealing member with ultraviolet-curable resin. In this case, the resin applied is filled, while being leveled.
In recent years, display panels have become thin. More precisely, both glass substrates used are as thin as 0.7 mm to 1.2 mm. It is therefore difficult to fill up the gap at the sealing member material with ultraviolet-curable resin in the method using a dispenser, only by leveling. If the gap at the sealing member cannot be filled up with the resin, a space will remain and electric corrosion can hardly be prevented. The ultraviolet-curable resin may drip down on the outer surface of both glass substrates. If this happens, the resin must be scraped off from the glass substrates.